There is a small tar road from Aberdeen Lower Reservoir to Wanchai Gap. The direct route is not that interesting but there are paths left and right, giving you enough chance to branch out into more remote areas. There are regular signboards with maps, so you can't really get lost. The Hong Kong Trail is crossing at some point.
You can also start at other locations in Aberdeen (eg at the cemetry).
You can also easly walk to the peak or the other side towards Wong Nai Chung Gap and further to Tai Tam if you are up for it.
besides lantau island, there are other islands like Po Toi Island and Tung Ping Chau that have really good hiking trails with beautiful scenery. i personally like Po Toi Island, the most southern point of hong kong. it's got several trails with varying degrees of difficulty. you can get there by ferry from either aberdeen, stanley, north point or kwun tong.
there's also a seafood restaurant at the end of the trail. lol. =D
Peel Rise down from the Peak to Aberdeen
In the evening: roundway around the peak.
Discobay up to the Golf Club, then through the golf club to Mui Wo.
Or Discobay along the water and the Yacht Club and Nim Shue Wan, via the Trappist Monastery to Mui Wo.
Lantau around the South-West end, starting behind the prison and ending in Tai O.
Search Google for waterfalls Hong Kong.
I'm a not-so-frequent hiker but with several years of experience. I enjoy the nature (and it is quite upset to the air pollution, i'd hardly see the blue sky nowadays)
Anyway, did anyone here spend a weekend in the flat located at Sunset peak? I passed them 2 weeks ago, and seemed no one there.